This actually makes more sense. JPA does not write to the data store until
either the EntityManager is closed or the transaction is flushed. Here's an
example using transactions:
EntityManager em = EMF.get().createEntityManager();
PrintWriter out = response.getWriter();
List<Dog> dogs;
try {
Dog newDog = new Dog("New dog!", 1);
EntityTransaction tx = em.getTransaction();
tx.begin();
em.persist(newDog);
tx.commit();
Query query = em.createQuery("SELECT FROM Dog"); // WHERE key =
:key");
dogs = (List<Dog>) query.getResultList();
// etc
Here are some examples:
http://openjpa.apache.org/builds/1.0.2/apache-openjpa-1.0.2/docs/manual/jpa_overview_em_lifeexamples.html
On Mon, Nov 23, 2009 at 8:18 PM, lp <[email protected]> wrote:
>
> > EntityManager em = EMF.get().createEntityManager();
> > PrintWriter out = response.getWriter();
> >
> > List<Dog> dogs;
> >
> > try {
> >
> > Query query = em.createQuery("SELECT FROM Dog WHERE
> > dogFriends = :key");
> > query.setParameter("key", key);
> > dogs = (List<Dog>) query.getResultList();
> >
> > dogs.size(); // Do this so we can eager load the list and
>
> solve it!
>
> running your code in my unit test i still get a 0 size result list.
>
> *until* i added the following in my unittest
>
> Dog user1 = new Dog()
>
> //blah blah
> em.merge(user1);
>
> em.close(); <-- needed to close existing em
>
> em = getEnityManager();
>
> //query now executes correctly
>
>
> it seems that the entity manager is not working as i expected.
> by doing em.close after making objects persistent and then getting new
> em, allowed the em.query to execute correctly.
>
> i am not clear of why the em behaviours like that, given the em.find()
> seem to find the correct object.
>
> any ideas?
>
> -lp
>
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>
--
Ikai Lan
Developer Programs Engineer, Google App Engine
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